In general, a voice recognition apparatus which recognizes an inputted voice and performs recognition according to a result of the recognition is known. For example, there has been provided a voice recognition apparatus which is mounted in a moving object, such as a vehicle, and which is constructed in such a way as to provide guidance for a driver according to an inputted voice in order to avoid the danger resulting from the driver's manipulation of a button. This type of voice recognition apparatus is equipped with a voice recognition unit which recognizes an inputted voice, and the voice recognition unit needs to discriminate between the inputted voice and disturbance, such as noise, in order to recognize the inputted voice.
Furthermore, there has been provided a voice recognition apparatus which is constructed in such a way as to, when performing voice recognition, time out if the user does not utter any sound even after a predetermined time (i.e., a timeout time) elapses. In such a voice recognition apparatus, when, for example, the user performs a voice input according to an utterance urging signal from the voice recognition apparatus, taking into consideration the fact that, generally, the time required for the user to utter the first one word after the user hears the utterance urging signal is longer than that required for the user to utter further words after that, in most cases, it takes much time for the user to utter the first one word and a timeout therefore occurs before the user utters the first one word.
To solve this problem, conventionally, there has been provided a voice recognition apparatus intended for vehicles which automatically adjusts a discrimination reference level used for discrimination between noise and voice according to the traveling conditions of the vehicle, such the velocity and the gear position of the vehicle, so as to surely discriminate between the inputted voice and noise (surely recognize the inputted voice) throughout the vehicle's velocity range from a low velocity to a high velocity (for example, refer to patent reference 1).
In addition, there has been provided a voice recognition apparatus which is constructed in such a way as to make timeout times variable in order to prevent a timeout from occurring before the user utters the first one word, particularly to lengthen a timeout time which defines a time interval during which the user has to utter the first one word (for example, refer to patent reference 2).    [Patent reference 1] JP, 57-30913,A (see pp. 2 to 3 and FIGS. 3 and 4)    [Patent reference 2] JP, 58-50598,A (see pp. 2 and FIGS. 1 and 2)